Problem with multiple expand parameters

When getting build results using the REST API I can't use multiple expand parameters.

Example (works)
/builds/rest/api/latest/result?label=productiondeploy&buildstate=successful&expand=results.result.comments.comment

Example (works)
/builds/rest/api/latest/result?label=productiondeploy&buildstate=successful&expand=results.result.jiraIssues

Example (does not work)
/builds/rest/api/latest/result?label=productiondeploy&buildstate=successful&expand=results.result.comments.comment,results.result.jiraIssues

In the example that does not work only jiraIssues are expanded. Comments does not expand.

IMHO the problem is the implementation of DefaultExpandParameter.parse which always put's new item to the parameters map without checking if something is there already.